Electronic devices comprising active organic materials are attracting increasing attention for use in devices such as organic light emitting diodes, organic photoresponsive devices (in particular organic photovoltaic devices and organic photosensors), organic transistors and memory array devices. Devices comprising organic materials offer benefits such as low weight, low power consumption and flexibility. Moreover, use of soluble organic materials allows use of solution processing in device manufacture, for example inkjet printing or spin-coating.
An organic light-emitting device (OLED) may comprise a substrate carrying an anode, a cathode and an organic light-emitting layer between the anode and cathode comprising a light-emitting material. Further layers may be provided between the anode and the cathode, for example one or more charge-injection or charge-transport layers.
During operation of the device, holes are injected into the device through the anode and electrons are injected through the cathode. Holes in the highest occupied molecular orbital (HOMO) and electrons in the lowest unoccupied molecular orbital (LUMO) of the light-emitting material combine in the light-emitting layer to form an exciton that releases its energy as light.
A light-emitting electrochemical cell (LEC) may have a structure similar to that of an OLED, and further has mobile ions in the light-emitting layer, which may be provided in the form of a salt and an ion-conducting polymer blended with a light-emitting material. The cations and anions of the salt may respectively p- and n-dope the light-emitting material, which may provide for a low drive voltage.
U.S. Pat. No. 5,900,327 discloses a LEC comprising the polymer BDOH-PF:

The ethylene oxide side groups of BDOH-PF are said to improve compatibility with the ion-conducting polymer poly(ethylene oxide) and increase solubility of the polymer in common organic solvents.
Suitable light-emitting materials include small molecule, polymeric and dendrimeric materials. Suitable light-emitting polymers for use in the light-emitting layer include poly(arylene vinylenes) such as poly(p-phenylene vinylenes) and polyarylenes such as polyfluorenes.
The light emitting layer may contain a semiconducting host material and a light-emitting dopant wherein energy is transferred from the host material to the light-emitting dopant. For example, J. Appl. Phys. 65, 3610, 1989 discloses a host material doped with a fluorescent light-emitting dopant (that is, a light-emitting material in which light is emitted via decay of a singlet exciton) and Appl. Phys. Lett., 2000, 77, 904 discloses a host material doped with a phosphorescent light emitting dopant (that is, a light-emitting material in which light is emitted via decay of a triplet exciton).
Hosts for luminescent dopants include “small molecule” materials such as tris-(8-hydroxyquinoline)aluminium (“Alq3”) and non-conjugated polymers such as polyvinylcarbazole (“PVK”).
Conjugated polymers (that is, polymers in which adjacent repeat units in the polymer backbone are conjugated together) may also be used as host materials. Such conjugated polymers may possess numerous advantageous properties such as solubility, which allows the material to be deposited by solution coating or printing techniques, including processes such as spin-coating or inkjet printing, and high conductivity.
WO 2005/013386 discloses an organic light-emitting device comprising a host polymer material and a luminescent metal complex wherein the polymer material may comprise non-planar repeat units or partially or fully non-conjugated repeat units in order to reduce conjugation of the polymer.
WO 2011/141709 discloses a light-emitting composition comprising a host polymer and a light-emitting dopant wherein the host polymer comprises conjugating repeat units and non-conjugating repeat units, and wherein the non-conjugating repeat units comprise an at least partially saturated ring. The presence of the non-conjugating repeat units is stated to increase the HOMO-LUMO bandgap of the polymer.